Starman -
I have had multiple affairs. I didn't think of them as affairs at the time, as my partner and I had agreed to have a polyamorous relationship. Nonetheless, they were affairs, and I eventually ended them and NCed all the affair partners that I could.
So. Let's see. The summary: Three EA/PAs (all with men), two EAs (both with women. All of the OP in my scenario were also married or partnered.
Now, having said that, please understand that my partner was fully aware of each of these relationships. I offered, and provided, as much detail as she wanted regarding the relationships and my emotions in them. She reacted with varying degrees of concern and upset, and also with varying degrees of acceptance and support.
Did her reactions really cause me to decide that this was not the way I ought to be leading my life? Yes and no. I came to realize, as I came out of the fog of the last (and truly devastating) EA, that this simply was not a path that was leading me to the things that I want in my life. I had also, throughout my affairs, changed specific behaviors that had caused my partner pain. Sometimes it took me some time to get it through my head, but I -did- make the changes.
So. Just because someone has had multiple affairs, does that mean they need to have a personal meltdown before they can move on to be a spouse? I don't know. I don't think it took that for me. It was just a growing unease with the life I was living, and a growing feeling that it did not really satisfy me.
Sadly, I came upon that knowledge at about the same time as my partner was beginning her relationship with OM. And I supported it because she deserved the chance to have that kind of relationship, too.
I said many times that I was terribly afraid that I was supporting the destruction of our marriage. Right now, it looks like I was absolutely right even though she swore to me that wasn't what was going to happen.
So. I've learned, I've grown, I've been burned black in the fire of this relationship that has become an affair. It became an affair, for me, during the month before DD was born, when WP scheduled every minute of her free time with him instead of with me. How do I know she did that? I sat in the room and wrote on the calendar while they scheduled it. It was a very, very bad day. One of many.
And I had already learned, before that, that my own extramarital relationships were not satisfying to me. Nowadays, I have neither those nor my marriage. Life is very different than it was a couple of years ago. And I'm okay with that difference.